The largest contributions will go to the Red Cross and the Salvation Army, which are each set to receive $300,000 according to a statement.

Other recipients include Reach Out America, an aid distribution organization, and Samaritan's Purse, a Christian relief group headed by evangelist Franklin Graham. The Houston Humane Society, Catholic Charities and the ASPCA are among the other organizations due to receive donations from Trump.

"The President and first lady witnessed the work of some of these groups first hand while visiting with hurricane survivors, first responders, volunteers and federal, state and local officials, and are proud to further assist the recovery efforts in Texas," the White House said in a statement.

The million-dollar batch of contributions amounts to one of the largest personal donations from a sitting president. Trump has visited Texas twice since Harvey made landfall, meeting state and local authorities and greeting some displaced residents.

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Trump's reelection campaign encouraged his supporters to make donations themselves in the immediate aftermath of the storm.

Trump has come under scrutiny in the past for charitable donations, including allegations he often didn't follow through on promised contributions after announcing them publicly. A promised donation to veterans' groups during last year's presidential campaign didn't materialize until months later after questions from reporters.

Trump has made good on a vow to donate the entirety of his presidential salary since taking office.

The White House said on Wednesday that Trump selected the recipients for Harvey relief efforts based in part on recommendations from members of the White House press corps, who were asked to put forward causes worthy of his donation.

Trump's longtime secretary Rhona Graff, who still works at the Trump Organization, has begun phoning nonprofit groups that will receive a personal donation.

"We just received notification by phone that a personal donation from President Trump has been made to Direct Relief and a check is being sent by mail," Direct Relief spokesman Tony Morain told CNN on Wednesday afternoon.

He confirmed Graff made the call.

CNN has reached out to the other organizations to confirm whether they have received a call or donation yet.